Furnace for dewatering and the like



April 5, 1932.l E. J'. FOWLER 1,852,646

l FURNACE FOR DEWATERING AND THE LIKE Filed March 8, 1928 3 Sheets-Sheet1 ,i y i. J

April 5, 1932. E. J. FowLl-:R

FURNACE FOR DEWATERING AND THE LIKE Filed March 8, 1928 5 Sheets-SheetApril 5, 1932. E. J. FowLER 1,852,646

FURNACE FOR DEwATE-RING AND THE :LIKE

Filed March 8; 1928 3 Sheets-Sheet 5 w95# MY@ ,Latter/Imago PatentedApr. 5, 1932 UNITED STATES PATENT OFFICE EDWARD J'. FOWLER, DECEASED,LATE 0F REDWOOD CITY, CALIFORNIA, BY EDITH MARY FOWLER, EXECUTRIX, OIF.`REJWOOD CITY, CALIFORNIA, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 NICHOLSENGINEERING .AND RESEARCH CORPORATION, OF NEW YORK, N. Y., A CORPORATIONOF DELAWARE l FURNACE FOR DEWATERIN G AND THE LIKE Application `ledMarch 8, 1928. Serial No. 260,083.

This invention relates to furnaces adapted vfor Various dewatering,drying and roasting operations, and the objects of the invention includethe provision of a furnace which will be inexpensive and relativelysimple in 'construction and highly elii'cient under various conditionsof operation.

Various further and more specific objects, features and advantages willclearly appear from the detailed description given below,-

taken in connection with the accompanying drawings which form a part ofthis speciflcation and illustrate, merely by way of example, oneembodiment of the apparatus of the invention.

The invention consists in such novel features, arrangements andcombinations of parts as may be shown and described in connection withthel furnace herein disclosed, by way of example only, and asillustrative of a preferred embodiment, together with such novel methodsand steps of processes as may also be described herein.

In the drawings, Fig. 1 comprises a vertical sectional view, partlybroken away, through a furnacev comprising one embodiment of theinvention;

Fig. 2 shows in elevation part of afurnace as of Fig. l; J

Fig. 3 is a sectional view taken substantially alon the line 3-3 of Fig.2; and

Fig. 4 sc ematically illustrates a plurality of drying or dewateringfurnaces operatively associated with a calcining furnace.

The body of the furnace may comprise a cylindrical casting or a suitablesheet metal shell, as at 10, insulated if desired. This shell, ofcourse, may be made of steel, brass,

various alloys, or special high temperature.

alloys, depending upon the service intended.

The cylindrical shell may be mounted upon a combustion chamber sectionof the furnace, as shown at 11. The'walls of the chamber may be made ofany suitable heat-resisting material, and a suitable source of heat,such as 18 comprising upright cones.

an oil or gas burner as at 12, may be mounted within the combustionchamber. The burn- `er may be accompanied by a supplemental At the topof the combustion chamber, a4

suitable heat-resisting dome member, as at 16, may be provided, whichalso serves in part as the bottom of the furnace per se.

Within the shell 10 a plurality of vertically spaced or superposedconical hearths may be provided, as at 17 and 18. The hearths 17 may bedetachably mounted and secured, as by key members 19, to a centralrotatable shaft 20, which shaft in turn may be suspended from the top ofthe furnace, as by a thrust bearing 21. The hearths 17 are accordinglydesigned to rotate with the rotatable shaft. On the other hand, thehearths 18 may be made stationary and may be aiiixed to or supportedfrom the cylindrical shell 10 by suitablebrackets, as at 22, which maybe bolted or otherwise alxed to the shell l0. It will be observed thateach of the hearths is substantially conical in shape, the hearths 17comprising inverted cones and the hearths While but. three of thehearths are illustrated in Fig. 1, for simplicity, it will be understoodthat a complete furnace will comprise many more hearths, for example asmany as from live to ten. It will also be understood that the hearthsneed not necessarily be conical in shape, so long as they comprisesubstantially surfaces of revolution for proper cooperation with rabblemeans hereinafter described.

The hearths 17 shown may be integrally formed with hub portions, as at23, embracing the shaft 20, so that the lower portions of the conicalarea comprise, in effect, a receptacle capable of retaining considerablebodies of liquids or the like. The hearths 18, for the same purpose, maybe integrally formed with peripheral upstanding flanges, as at 24.However, the hearths 18 are preferably made with central dischargeopenings, as at 25, through which the shaft 2() extends and throughwhich material after treatment on the hearth is discharged to the hearthnext below. The material is discharged from the hearths, such as 17 bycausing the same to fall over theperipheral edges of the hearth to thenext hearth below.

The rabbling means for advancing the material under treatmentsuccessively over each of the hearths may comprise both stationary androtatable rabble arms, as at 26 and 27, respectively, the rabble arms 26being removably mounted so as to extend through apertures, as at 28, inthe shell 10. Removable .or fixed rabble teeth of any desired orconventional form, as at 29, may be provided along each of the rabblearms. Exteriorly of the shell 10 the rabble arms 26 may be provided withflanged portions, as at 30, designed to be bolted to the exterior of theshell. These portions may also be provided with exterior cavities orsocket portions, as at 31, desi ned to be engaged by suitable tools orli ting means for removal of the rabble arms from the outside of thefurnace. It will be observed that the openings 28, although designed tobe normally covered by the flanges 30, are nevertheless of sufficientsize to permit the rabble arms to be .y removed as assembled units,including the rabble teeth. Accordingly, whenever any diiiculty shouldarise with any particular rabble arm, the whole rabble arm assembly maybe replaced by a spare without any considerable interference with theprocess going on. The rotatable rabble arms 27 at their inner ends maybe formed with detachable hook portions, as at 32, engaging suit'- ableapertures 33 and wedge members 34 as provided in spider members 35. Thespider members 35 in turn are detachably secured to the rotatable shaft20 by suitable keys in a manner similar to the attachment of therotatable hearths 17. Suitable clean out or observation doors, as at 36and 37, may also be provided opposite the various hearths. The rotatablerabble arms which are attached to the shaft may be removed through theseobservation doors without cooling the furnace.

At the top of the furnace a cover member, as at 38, may be provided,which also may serve as a supporting means for the thrust bearing 21and, in addition, as a supporting means for a suitable speed reductiongear assembly, as at 39, driven from a suitable source of power andserving in turn to drive the rotatable shaft 20, through suitable bevelgears, as at 40.

The material to be treated in the furnace may be introduced through afeed inlet, as at 41, extending through the furnace top 38, and thegases of the furnace may be taken oil" through a gas outlet, as at 42,also extending vthrough the furnace cover or top. The matterial aftertreatment in the furnace may fall from the periphery of the lower hearth17 onto the furnace bottom, as at 43, from which it may be scraped, asby a scraper 44, to a discharge spout 45. The scraper 44, as shown, maybe detachably secured to the underside of the periphery of the rotatablehearth 17, as by a suitable form of mortise and tenon joint 46, asillustrated.

In order to guide the lower end of the shaft 20 as suspended from thesingle thrust bearing 21, suitable guide rollers, as at 47, may beprovided to engage the peripheral edges of one of the lower rotatablehearths 17 The guide rollers 47 may be mounted in suitable removableflange plate members, as at 48, extending through openings in thefurnace wall, as at 49. Four or more of the guide rollers', as at 47,may be placed around the periphery of the lower hearth, as indicated.The plate members 48, together with the guide rollers, which arerotatably mounted therein, may be readily applied and adjusted orremoved from the exterior of the furnace for purposes of replacement orrepair, etc.

The material treated in the furnace in passing down through the furnaceis rabbled inwardly and outwardly, respectively, over the alternatelyarranged upright and inverted conical hearths, and in the meantime hotair and other heated gases from the combustion chamber 11 are permittedto pass up through an opening, as at 50, through the dome member 16, andthence upwardly through the furnace by passing around the peripheries ofthe rotatable hearths and through the central discharge openings 25 ofthe stationary hearths. By using a single thrust bearing, as at 21, forsuspending the rotatable parts from the top of the furnace, the lowercentral portion of the furnace is left unobstructed, permitting the hotgases to be freely and symmetrically applied to the lower hearth. Inaddition, it will be observed that, by the use of a relatively largenumber of hearths, adequate capacity may be obtained with hearths ofrelatively small diameters. These conditions cooperate in precluding anytendency of the hot gases to confine their paths of travel to certainchannels to the exclusion of other portions of the furnace, andconsequently a uniform heating of the entire area of each hearth isinsured- The furnace is well adapted for general industrial uses, suchas dewatering and drying of very wet material, such as slimes, slurriesand mixtures of waters and solids, and also for ordinary dryingoperations of material ,containing relatively smaller quantities ofwater. Also the furnace is adapted for drying of crystalline chemicalsand for the evaporation of chemical liquors, in many in,

stances. Furthermore, l ert heated gases may be passed through thefurnace, where other ascending hot gases might cause excessivecombustion or undesired chemical changes.

It will be observed that each hearth may be dished or cupped to thedesired extent, depending upon the character of the material to betreated, so that such material as first applied to the deep area of thehearth will be gradually worked by the rabble teeth toward the shallowor discharge areas, and will be discharged at a rate depending upon thespeed of rotation and quantity of material admitted and the angle of theconical hea-rths, the heat applied, etc. The solid material will, ofcourse, be more quickly advanced by the rabble teeth, so that the liquorwill remain longer on each hearth and accordingly will be given ampletime for the desired evaporation before being advanced to the succeedinghearths. V v

In drying or dewatering operations, considerable quantities of air areordinarily required at a temperature of over 212J F. at the upperhearths, and the supplies of such air from the combustion chamber may beregulated as by burning extra fuel when necessary. l

All products of evaporation may be passed out of the furnace through thelarge gas outlet 42 at the furnace top and the dried residue through thedischarge spout 45. The arrangement of the hearths and rabbles preventsthe clogging of material on any hearths, since substantially all hearthareas are reached by rabbles, thus keeping all material constantly inmotion and at the same time permitting the hearth areas to be fully exposed to the heated air or gases.

` This furnace is adaptable for use in conjunction with calcining androasting furnaces to d-eliver dried material to the top drying hearth ofsuch furnaces. Furthermore, when thus used, the heated air as dischargedfrom the air cooled rotatable shafts and rabble arms of such calciningfurnaces may be readily in special cases, in-

`used as a drying medium in this dehydrating furnace merely byconducting such heated air or gases to the inlet 15. Furthermore, ifdesired, all of the outlet gases from the calcining or roasting furnacesmay be passed through the drying furnace, as above described, forsupplying the necessary heated air for carrying olil the moisture- Whenthus coordinated with the operation of the calcining or roastingfurnaces, this Ydehydrating 'furnace is well adapted as a dust collectorfor the roasting furnace discharge gases. Inasmuch as the dischargegases gradually work their way up through this dehydrating furnace, thedust will be accumulated by the wet material on the hearths and thusavoiding the use of special dust accumulating means. In roastingoperations 4carried on in connection with certain ores, for example,flotation sulfide concentrates containing as much as twenty per cent ofwater, the effective capacity of the roasting furnace can besubstantially increased by first passing the wet material through adrying furnace, as above described, and furthermore the drying will beaccomplished substantially without permitting caking or excessivelumping of the material, which would tend to preclude thorough treatmentduring the roasting operation, particularly if conducted rapidly.

It will be understood that the burner l2 indicated in the drawings ismerely illustrative of one example. Other sources of heat may beutilize-d, such as coal or wood fires on standard grates. Furnacetemperatures may behraised to any desirable practical degree, and forhigh temperatures shaft and rabble arm cooling arrangements known in theart may be resorted to, in which event the furnace may be utilizedtoroast various mate rials or even to liquefy certain materials.

The alternately arranged conical hearths 17 and-18 permit of aconstruction which avoids the use of small peripheral port areas commonin other t es of furnaces, and consequently the possibility of cloggingand caking is eliminated.

A group of the above described furnaces may be conveniently arrangedaround the circular wall of a large calcining furnace, so that outletgases from the calcining furnaces may be distributed between thedehydrating furnaces, as desired. Such an arrangement is illustrated inFig. 4, in which a calcining furnace is schematically indicated at 51, adrying furnace being indicated as at 52. Ma- 103 terial carriers areindicated as at 53 for conveying the dried or dewatered material fromthe furnaces 52 to the calcining furnace. Conduits as at 54 serve toconvey the gases discharged from the calcining furnace to the 113 inlets15 of the drying furnaces. If desired,- heated gases from the centralshaft ofthe calcining furnace, which have been used for cooling theshaft and rabble arms, may be conveyed by conduits as at 55 tothe baseof 113 the furnaces 52 as shown. Suitable damper regulating means may beprovided in the conduits 54 and 55 as at 56 and 57 respectively. Thecalcining furnace may be of a type well known in the art, such forexample as is 13 shown in numerous patents to Herreshoff, hence thedetails thereof need not be here described. l

The above described furnacekmay also be used in the preliminarytreatment of fullers earth whichis to .be revivified, particularly wheresuch fullers earth is too oily to be conveniently treated in an ordinaryroasting furnace. For such uses, a steam jet ma be introduced in theabove described furnace 13 `tab1e1`hearth mounted on said shaft comandthe furnace used for-reducing the oil content of the fullers earth,which may later be more rapidly treated in a roasting furnace with moreaccurate control of the roasting temperatures.

While the invention hasbeen described in detail with respectftoparticular preferred examples and methods of operation which givesatisfactory results, it will be understood by those skilled in the art,after understanding the invention, that various changes andmodifications may be made Without departing from the spirit and scope ofthe invention, and it is intended therefore in the appended claims tocover all such changes and modifications.`

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1.y A drying furnace comprising a plurality of superposed alternatelyarranged rotary and stationary hearths, alternate hearths beingrespectively also substantially of upright and inverted cone shapes, thehearths'of upright conical shape having central discharge openings andrabbling means cooperating with each hearth.

2. In a furnace having a rotatable hearth, a relatively stationaryrabbling arm assembly carrying rabble teeth and extending through thefurnace Wall for cooperation with said hearth, and means for detachablyaflixing said assembly to the exterior of the furnace Wall, the furnaceWall having an opening normally closed by the arm supporting portionssuch opening being of a size permitting the assembly to be removed tothe exterior of the furnace as a unitary structure including its rabbleteeth.

3. A multiple hearth furnace including a plurality of rotatable hearthsmounted upon a rotatable shaft suspended from a thrust bearing at thetop of the furnace.

4. A multiple hearth furnace including a plurality of rotatable hearthsmounted upon a rotatable shaft suspended from a thrust bearing at thetop of the furnace, and means engaging alower hearth substantially atits peripher for retaining the rotatable hearth and sha assembly againstswinging Imovement.

5. A furnace comprising a rotatable hearth and shaft assembly suspendedfrom a bearing at the upper part of the furnace, and a plurality ofguiding means engaging a lower part of the assembly at points spacedsubstantially from the axis of rotation.

6. In a furnace having a rotatable hearth, a relatively stationaryrabbling arm extending through the furnace Wall for cooperation withsaid hearth, and means for detachably aixing said arm to the exterior ofthe furnace Wall.

' 7. In a furnace having a rotatable shaft, a

prising a substantially annular concave casting embracing the shaft anddetachably keyed thereto.

8. In a furnace having a rotatable shaft, a rotatable hearth mounted onsaid shaft comprising a substantially annular concave casting embracingthe shaft and detachably keyed thereto, and rotatable rabbling meansalso detachably secured to said shaft for cooperation with otherhearths.

9. In a furnace having a rotatable hearth, an enclosing Wall having anopening therethrough, a relatively stationary rabbling member extendingthrough said opening in the Wall for cooperation with said hearth, and acover for said opening, s'aid rabbling member being carried bv saidcover and said cover beiig detachably affixed to the exterior of the Wal.

10. A furnace having a rotatable shaft, a rotatable hearth mounted onsaid shaft cornprising an integral and conical casting embracing theshaft and detachably secured thereto at the center of he hearth.

1l. In a drying furnace having a vertically extending rotatable shaft, aplurality of rotatable hearths mounted on said shaft in spacedpositions, each of said hearths comprfsing an integral conical memberapertured at the center to embrace the shaft and slidable along theshaft into position thereon, and means for detachably securing eachhearth in the desired position including a vertically extending sleeveencircling the shaft and integral With the hearth.

l2. In a drying furnace having a vertically extending rotatable shaft, aplurality of rotatable hearths mounted on said shaft in spacedpositions, each of said hearths comprising a relatively thin integralmetallic member apertured and provided with a vertically extendingintegral sleeve at its center for embracing the shaft, the hearths beingslidable into position along the shaft, and means for detachablysecuring the sleeves of each of said hearths independently to the shaft.y

13. In a furnace having a rotatable shaft, a rotatable hearth mounted onsaid shaft comprising a substantially annular inte-gral castingembracing the shaft and detachably secured thereto, means for rabblingmaterial under treatment on said hearth and for discharging the samefrom the periphery thereof to a surface beneath the hearth forsupporting the material under treatment, and a member suspended frolnthe periphery of said hearth for advancing such material along and ofl'from said supporting area.

14. A furnace comprising an enclosing Wall and a plurality of superposedand relatively rotatable hearths therein, the lowermost of said hearthsbeing rotatably carried by a vertical shaft, a substantially annulartrough being provided at the bottom of the furnace beneath saidlowermost hearth, a furnace outlet opening from said trough, and ascraper member detachably carried at the periphery of said lowermosthearth for advancing the material under treatment along said trough andto said outlet.

In testimony whereof I have signed my name to this specification.

EDITH MARY FOWLER, Ewecam' of the Las# Wz'ZZ and Testament of Edward J.Fowler, Deceased. a

